In a known image forming apparatus such as a laser printer, an electrostatic latent image is formed on a surface of a photosensitive drum, toner is supplied from a toner cartridge to the latent image, and the electrostatic latent image is developed into a toner image on the surface of the photosensitive drum. Then, the toner image is transferred to a sheet, so that image is formed on the sheet.
The toner cartridge includes a toner chamber, a developing chamber, and an agitating member. The toner chamber contains toner therein. The developing chamber communicates with the toner chamber via a toner supply opening. The agitating member is rotatably disposed in the developing chamber, and is configured to stir toner in the toner chamber. Toner in the toner chamber is stirred and moved toward the toner supply opening by rotation of the agitating member. The toner is supplied to the developing chamber via the toner supply opening. Toner supplied into the developing chamber is formed into and carried as a thin layer on a surface of a developing roller. The thin layer of toner on the surface of the developing roller is brought in contact with the surface of the photosensitive drum by rotation of the developing roller, and thus is supplied to the electrostatic latent image formed on the surface of the photosensitive drum.
Thus, the agitating member is required to efficiently convey toner in the toner chamber to the toner supply opening.
For example, there has been proposed an agitating member in which a plurality of flexible sheet pieces is arranged on a shaft. In the agitating member, flexibility of the sheet pieces disposed at both ends of the shaft is less than that of other sheet pieces, so as to improve the stirring force at both ends of the container where toner is stored.
Another agitating member is proposed that includes a flexible member that is rotatably and freely disposed within a toner supply container in order to carry toner to a toner supply port. The flexible member has a plurality of slits to define separate areas, each having a hole therein. Thus, toner can be collected toward the middle in the toner supply container, so that toner can be used efficiently.
However, in the first proposed structure, a direction of toner conveyance by a center sheet piece is the same as the direction of toner conveyance of each end piece, and it is difficult to provide a component along the rotation shaft to the direction of toner conveyance by the agitating member.
On the contrary, in the second proposed structure, the flexible member includes a hole and thus stiffness around the hole is weak. It may be possible to give the component along the rotation shaft to the direction of toner conveyance by the agitating member, however, with the provision of the hole, toner conveyance force by the flexible member may be reduced and an adequate quantity of toner cannot be conveyed to the toner supply port.